Number bases

There are 24 NRICH Mathematical resources connected to Number bases
Sometimes we lose things
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Sometimes we lose things

Age
7 to 11
Challenge level
filled star filled star filled star
Well now, what would happen if we lost all the nines in our number system? Have a go at writing the numbers out in this way and have a look at the multiplications table.
A Story About Absolutely Nothing
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A Story About Absolutely Nothing

This article for the young and old talks about the origins of our number system and the important role zero has to play in it.
The Knapsack Problem and Public Key Cryptography
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The Knapsack Problem and Public Key Cryptography

An example of a simple Public Key code, called the Knapsack Code is described in this article, alongside some information on its origins. A knowledge of modular arithmetic is useful.
Learn About Number Bases
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Learn About Number Bases

We are used to writing numbers in base ten, using 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. Eg. 75 means 7 tens and five units. This article explains how numbers can be written in any number base.